I've done both, but it was at the RDS in Dublin in 1993. Mind you I've been to 81 shows over the course of almost 20 years of which, many were in GA. I'm a big, strong girl of hearty Scandinavian, Irish and German stock -- no shrinking violet.
That said: The Dublin GA swarm during the show was the most vicious crush I've ever been involved in!
After experiencing Dublin GA on night 1, I deliberately swapped my night 2 GA for a seated ticket so I could enjoy the show more.
If you can get right along a railing, there are diagonal braces on the inside of the railing (the part that faces the band) that you can hold onto and try to keep from being moved en masse with the crowd swell, but if you've nothing to hold onto -- you're going to be miserable.
I went to 11 UK shows in a row that summer, from Aug 7 in Glasgow thru Aug 28 in Dublin -- all GAs (except that last night in Dublin) and nowhere from Wales to London to Cork did I see as high of a number of people pass out and have to be taken out of the crowd.
My advice for Dublin: SAVE YOURSELF! GET A SEATED TICKET! LOL
Another consideration -- if you're going to Dublin for the show (i.e. you're from somewhere else) you'll also appreciate being able to enjoy your day in town, rather than queued up beside a brick wall all day instead.